1. Field of the invention
This invention relates, generally, to an interface member worn upon the residual limb of an amputee to provide a cushion between the residual limb and a prosthesis. More particularly, it relates to a transparent silicone interface.
2. Description of the prior art
Prosthesis sockets are hard, rigid devices that receive the residual limb, also known as the stump, of an amputee. Individuals requiring the use of such sockets typically wear several layers of socks over their residual limbs in an effort to provide a cushioning means between the stump and the socket; the socks work reasonably well as a cushioning means but do not serve the function of holding the socket onto the residual limb.
Accordingly, several inventors have developed means for cushioning the residual limb and holding the socket onto the limb. For example, U.S. Pat. No. 4,923,475 to Gosthnian et. al. discloses a stump-receiving socket having a plurality of inflatable bladders, each of which includes a relatively soft, flexible membrane made of a suitable material such as polyurethane. The idea behind the design is to maximize the weight-bearing area while minimizing or eliminating pressure points through the judicious use of the inflatable bladders.
The materials used to provide the cushioning means tend to exhibit poor anti-tear properties. Thus, U.S. Pat. No. 4,923,474 to Klasson et. al. discloses a cushioning member made of an elastomeric material having a fiber embedded therein to increase its strength.
Although some of the earlier interface members have a shape and thickness similar to that of the present invention, they are opaque and thus pose problems to the prosthetist when fitting the interface member to a patient. Most of the earlier interface members also lack strength and durability. The earlier members that do have adequate strength and durability are expensive to manufacture because they rely upon fabric embedded within the material of which they are made to supply the needed strength.
Moreover, the attachment of the interface members of the prior art to sockets has proven problematic. The conventional device employed to secure the interface member to the socket is typically bonded to the lowermost end of the interface member; it is releasably connected to the socket. The device is formed of a nonsilicone material, however, and suitable bonding techniques for bonding such a device to a silicone interface member have not been found.
What is required, then, is a transparent silicone socket interface member having strength and durability derived from its formulation and not from fabrics embedded therein. A need also exists for a new method of securing a connector device to the lowermost end of a socket interface member. A transparent, fabric-free socket interface member having enhanced strength and durability would enable the prosthetist to observe socket pressures and tensions, especially in high load areas. Scar tissue, skin grafts, and invaginated areas could be easily monitored to ensure total contact, and silicone putty could be applied where needed to eliminate voids. The position of the interface member and all putty applications could be checked for proper positioning during and after socket application.
However, in view of the state of the art at the time the present invention was made, it was not obvious to those of ordinary skill in this art how such a silicone suction socket could be provided, nor was it obvious that a clear silicone suction socket should be provided.